Shoulder arthroplasty for glenohumeral osteoarthritis: results from a comprehensive survey in Belgium and the Netherlands.

The purpose of this survey in Belgium and the Netherlands was to assess treatment variation in glenohumeral osteoarthritis between experienced and less experienced orthopedic surgeons, and to investigate perioperative treatment after shoulder arthroplasty in a large group of orthopedic surgeons. Orthopedic surgeons specialized in shoulder surgery were invited to complete a survey between November 2013 and February 2015. Seventy-one percent of the approached surgeons com-pleted the survey. Less experienced surgeons (< 6 years) and surgeons from the Netherlands find patient characteristics (e.g. smoking p=0.01) more relevant than more experienced surgeons (≥ 6 years) and surgeons from Belgium. Less experienced surgeons will less likely (p=0.001) perform resurfacing arthroplasty compare to experienced surgeons. The less and the experienced surgeons use similar indications for a reverse shoulder arthroplasty regarding age limit and cuff arthropathy without osteoarthritis. Less experienced surgeon will more likely (p=0.003) prescribe a low molecular weight heparin during the hospital stay after a shoulder arthroplasty. In this survey, we found a decrease in the use of resurfacing arthroplasty and a strong increase in the use of reverse shoulder arthroplasty. Besides, there is little consensus concerning pre-operative planning, patient characteristics, surgical technique, and patient reported outcome measures. Level of evidence: IV.

Shoulder prostheses treating cuff tear arthropathy: a comparative biomechanical study.

UNLABELLED: Painful cuff tear arthropathy (CTA) affects the independence of the elderly. Surgical treatment often consists of joint replacement, the functional outcome of which remains variable. Knowledge of the biomechanical properties of the different prosthetic designs can guide the orthopaedic surgeon in the choice of implant to predict its clinical result. A 3-D computer model of the glenohumeral joint is used to analyse the moment of the deltoid muscle in the scapular plane. A geometrical 3-D ball-and-socket model of the shoulder joint was used to calculate (1) the angle-force relationships, (2) the moment arm of the deltoid muscle and (3) the moment of the deltoid muscle components, for increasing degrees of arm elevation in the scapular plane. In this 3-D model, a clinical thoraco-scapular rhythm analysis was implemented, based on measurements in normal subjects, patients treated with an anatomical prosthesis and patients treated with an inversed delta III prosthesis. These data were compared for 10 different prosthetic treatment options. RESULTS: Muscle angle-force curves show a favourable slope in non-anatomical prosthetic designs, where the centre of rotation of the glenohumeral joint is medialized, the deltoid muscle is elongated and the humeral shaft is lateralized. On the contrary, anatomical prosthetic designs do not perform well in this computer analysis. CONCLUSIONS: From a biomechanical point of view, a shoulder prosthesis which medializes the centre of rotation, lengthens the deltoid muscle and increases the deltoid lever arm, results in a significantly more powerful abduction of the shoulder, despite complete loss of rotator cuff function. RELEVANCE: This study explains why a successful functional outcome can be expected in CTA with a reversed prosthesis.

About the variability of the shape of the glenoid cavity.

The morphology of the glenoid cavity is highly variable, and no consensus exists regarding how to classify the different forms. We examined 98 dry scapulae to identify a common morphological entity and to define reproducible bony references of the glenoid cavity. The glenoid cavities were photographed perpendicularly in a standardized fashion. The bony peripheral rim was studied on these two-dimensional images, defined by randomly chosen points in order to define one or more circles. This study showed that only the peripheral rim of the inferior quadrants of the articular surface was found to be located on a circle ( P=0.926) with a radius of 12.8 mm (SD 1.3 mm). Defining the center of this circle appeared to be more reliable (ICC 0.98) than determining the middle point of the longitudinal axis (0,0) between the most cranial and most caudal points, defined as Saller's line (ICC 0.89). The distance of the center of this projected circle to the middle point of Saller's line had a unimodal distribution, suggesting the existence of only one glenoid cavity morphotype. We then investigated the relationship between the center of the circle and the area of subchondral bone thickening under the bare spot, the so-called tubercle of Assaki. Ten phenolized cadaveric glenoid cavities were examined with computed tomography. A circle was projected on the first image showing the bony peripheral rim, and this circle was copied on the consecutive slices until the tubercle of Assaki came across. The center of the circle was located within the area of the tubercle of Assaki, in all but one specimen. To investigate the clinical implications of this finding, the cadaver specimens were used to compare the position of the center of the circle with the postulated center of implantation according to the literature, and to the reference guide for a commonly used total shoulder prosthesis. The center of the circle was consistently situated more distal than the postulated center of the guide (mean 5.5 mm, range 4-8 mm) and the middle point of the glenoid cavity (mean 2 mm, range 1-3 mm). These findings could offer a reproducible point of reference for the glenoid cavity in osseous anthropometry and a valuable reference in shoulder replacement surgery, and might help in the definition of osseous glenohumeral instability.

[Results of an inverted shoulder prosthesis after resection for tumor of the proximal humerus]. / Résultats d'une prothèse d'épaule inversée après résection pour tumeur de l'humérus proximal.

PURPOSE OF THE STUDY: Treatment of primary bone tumors of the proximal humerus is a major challenge, both in terms of oncological cure and limitation of functional handicap. Extracorporal radiation and reimplantation have provided satisfactory results for the treatment of bone tumors and the inverted shoulder prosthesis has be found to be effective in treating rotator cuff deficiency. We therefore assessed patients treated with a combination of these two treatments in order to search for a better functional outcome. MATERIAL AND METHODS: Conservative resection of the tumor with reconstruction using an inverted shoulder prosthesis was performed in six patients with a tumor of the proximal humerus of type Ia or Ib in the Malawer classification or type S3-S4-S5 in the Musculoskeletal Tumor Society classification. Patients whose tumor involved the deltoid or the glenohumeral joint were not considered for this procedure. The series included four men and two women (4 left and 2 right shoulders) aged 51 years on the average at the time of surgery. RESULTS: Mean follow-up was 12 months. The mean age- and sex-adjusted Constant score was 74% (70-85%). The patients were generally satisfied and were able to continue their daily activities. There were two displacements, one of which was diagnosed immediately and reduced without anesthesia. An abduction pad was worn for six months after reduction. The post-operative period was uneventful. No local recurrence has been observed. DISCUSSION: Our results compared favorably with other therapeutic options for resection-reconstruction reported in the literature: functional outcome was better and more predictable, at least in the short term; oncological results were satisfactory although the follow-up is short, particularly for the three primary malignant tumors. It is known however that the long-term oncology result depends on the quality of the resection and the efficacy of the extracorporeal radiation. Shoulder motion outcome was the least satisfactory in patients who experienced peri-operative complications. We were unable to find any relation between less satisfactory functional outcome and the number of surgical procedures for local recurrence before extracorporeal radiation and arthroplasty (deltoid dystrophy). Normal deltoid function appeared to be crucial for optimal functional outcome with this prosthesis which allows sacrifice of the rotators. The rate of complications was low and recovery of active shoulder movement was more rapid. Despite the short-term nature of these results, and despite the risk of loosening, the inverted shoulder prosthesis appears to be an interesting therapeutic option for these patients.